1. Field of the Invention
The present invention relates generally to a fluid coupling for connecting a hose to a service port, and more particularly to a fluid coupling that can be quickly connected and disconnected, and that has a valve that can be opened only when the coupling is securely connected with a service port.
2. Description of the Prior Art
Automotive air conditioning systems frequently have charging ports that allow a person maintaining the system to add or remove refrigerant used by the system. Charging ports may also provide a convenient connection point to make measurements of pressures in the system using a pressure gauge.
A coupling, or coupler, is a device that fits onto a charging port. The coupling is typically connected to one end of a hose. The other end of the hose may be connected to a tank of refrigerant, a pressure gauge, or a manifold.
The coupling may contain a coupling valve that can be opened and closed to control the flow of fluid. When the coupling valve is open, refrigerant may pass through, into or out of the air conditioning system by way of the charging port. In preferred designs, the valve in the coupling port may be operated with one hand, without having to see the coupling to locate the valve handle, or see if the valve is opened or closed. It is also preferred to have a coupling design that permits connecting to the port and operating the valve without a substantial change in the user's grip on the coupling and hose. This allows easy connection and valve operation with one hand, which is an advantage in a location where the user cannot see the port.
The coupling port on the air conditioning system may also have an interior valve. A typical type of valve found in a charging port is a Schroeder valve. The Schroeder valve may be opened and closed by depressing and releasing a valve stem inside the charging port. The Schroeder valve inside the charging port is preferably operated together with the operation of the coupling valve. In some prior art couplings, the Schroeder valve is operated as part of the attachment process. This has the disadvantage of opening the Schroeder valve too soon, before the coupling is completely attached, which means that the force needed to attach the coupling increases due to the pressure of the fluid in the charging port. The charging port may also have an exterior circumferential groove that permits the use of a quick connect/disconnect mechanism that engages the groove.
When the coupling is connected and disconnected with the charging port, it is desirable to minimize refrigerant leakage due to the cost of wasted refrigerant and concerns about the refrigerant damaging the environment. Refrigerant leakage is minimized by installing the coupling onto the charging port with both the coupling valve and the charging port valve in closed positions.
It is also preferred, for safety reasons and for reducing fluid waste, that the coupling securely attach to the port, and remain securely attached until the coupling valve is closed. A coupling that prevents the opening of the coupling valve until it is securely attached to the port is also preferred.
It is also desired for the coupling to be inexpensive to manufacture.
Therefore, there is a need for an improved fluid coupling with an internal coupling valve that is easy to install with a quick connection apparatus, that is easy to operate with one hand, and that includes safety features that prevent the opening of the coupling valve unless the coupling is securely installed on the charging port.